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Physics Classroom is making strides to make our site accessible to everyone. Our site contains 6 navigation areas. The Primary, Secondary, and Page Level navigations have a screen reader version of their nav structure that allows using the left and right keys to navigate sibling navigation items, and up or down keys to navigate parent or child navigation items. The others can be navigated using tabs. The Primary Navigation handles the first 2 levels of site pages. The Secondary (which is not always available) handles the 3rd and 4th level of structure. The Page level navigation allows you to navigate the current page's headings quickly. The Header Navigation contains the Light/Dark Mode toggle, Search, Notifications and account login. The Breadcrumb Navigation contains the breadcrumb of the current page. If the current page has a breadcrumb, you can get to it by skipping to the content and tabbing in reverse (shift plus tab). The Footer Navigation contains links such as Privacy, Contact, about and terms. Some resources contain an Audio Player that can be activated by holding down the T key for 3 seconds, and then using K to pause and resume. While not every area of Physics Classroom is usable purely from keyboard and screen reader, we are committed to continue work on making this possible. If you have questions or need additional help, please use this link to contact us.

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Classification of Matter - Directions

Using the Classification of Matter Concept Builder is quite simple. There are four different activities, each of which has a different emphasis and a different set of directions.





In the first activity - Matching Pairs - you are presented with 8 terms (four quantities and four units) that you must match. To do so, tap on two matching terms to highlight the table cell that the term is located in. If two (and only two) terms are highlighted, a Check Match button is displayed on the right side of the window. If you change your mind, you can tap on the cell a second time to deselect it. When you are satisfied with your answer, tap on the Check Match button. Your pairing will be checked and your progress will be updated and displayed on the right side of the window. Once you successfully match two terms, they are no longer available for subsequent matching. If you mis-match two terms, then you will have to start over. Each time you start over, the terms are re-randomized and appear in a different location in the table and you must begin with 0 matches. This will force you to concentrate on the successful matches that you have already made so that you match them successfully again if you have to start over. Once you successfully match all terms, you will be rewarded the trophy for Matching Pairs.

In the second activity - Scientific Notation - you have to do one of two things: convert a number expressed in scientific notation to standard notation or convert a number expressed in standard notation to scientific notation. You perform the conversions using the on-screen arrow buttons. There are buttons to move the decimal point and there are buttons to change the exponent on 10. The left and right arrow buttons can be used to move the decimal point in either direction. The up and down arrows (where available) can be used to increase or decrease the exponent on 10. Once you have made a change, a Check Answer button appears. If you wish to change your mind, then you can continue tapping on the arrow buttons. When you are satisfied with your answer, tap on the Check Answer button. Your answer will be evaluated, feedback will be given, and your Progress Report will be updated.

In the third activity - Measurement - you will be given a graphic of a measuring tool and asked to determine the measured value to the proper number of significant digits. There are six answer options provided. You can select an option by tapping on the value or by tapping on the radio button next to the value. Your selected option will be highlighted in red text. If you change your mind, you tap on the same option to deselect it or tap on a different answer option. As long as an answer is elected, the Check Answer button appears. When you are satisfied with your answer, tap on the Check Answer button. Your answer will be evaluated, feedback will be given, and your Progress Report will be updated.

Your goal is to earn "Stars" and to complete one or more activities. Stars are earned when you show success on a particular question. Once you show success on all the questions for a particular activity, you will earn the trophy for that activity.

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